The production of rearview mirrors for motor vehicles normally endeavors to achieve an especially high reflection factor or reflection value of the mirror so that objects to the rear can be clearly recognized. For this reason, such automobile mirrors are usually made on the basis of a highly transparent support or layer substrate material that is provided with a highly reflective metal coating, for example, consisting of silver or aluminum. In conventional automobile mirrors, this reflective coating can normally be applied onto the back of the layer substrate so that the coating is protected by the layer substrate and by the mirror frame against direct environmental effects, especially dirt. Such mirror systems can achieve reflection values of more than 85% in the spectral range of visible light. On the other hand, however, such highly effective rearview mirrors entail the problem that such high reflection values could cause the driver to be blinded at night by the headlights of cars behind him.
So-called non-glare rearview mirrors have been developed that are supposed to reduce the blinding of drivers at night. Particularly for this purpose, the mirrors can be tinted. With an eye towards the recent developments in headlight systems for motor vehicles, in which halogen headlights are becoming more and more widespread, blue tinting has now been developed for rearview mirrors. Such a blue tinted mirror reflects the halogen headlights of the traffic behind the car more weakly than daylight so that at night, a glare-reducing effect is achieved. In order to produce such a low-glare rearview mirror, there is usually an intermediate layer arranged between the reflective mirror coating and the layer substrate, said intermediate layer providing the appropriate color tinting of the mirror. Thus, rearview mirrors are known, for example, from German patent DE 34 36 011 C1, in which these intermediate layers are configured as dielectric layers along the lines of an interference system. As an alternative, semiconductor layers can also be provided as reflective coatings, which can likewise be combined with dielectric layers as the intermediate layer in order to tint the mirror.
As an alternative, in order to avoid or reduce the risk of glare, it has also been considered to produce metal mirrors in combination with fully colored glass or films. However, such mirrors are fairly complex to manufacture and assemble, as a result of which they have not found widespread use in the automotive sector as rearview mirrors. Another alternative approach for the production of such low-glare rearview mirrors is the integration of parts with a variable transmission into the mirror structure, whereby especially electrically controllable components in the form of electrochromic mirrors or LCD mirrors have been considered. However, these techniques are also quite demanding, especially in view of the requisite control measures that are supposed to bring about the achievable low reflection values exclusively in the concrete case of acute glare.
For these reasons, conventional rearview mirrors for motor vehicles are structured using the above-mentioned dielectric intermediate layers between the layer substrate and the reflective mirror coating. However, it has been found that even such mirror systems only inadequately live up to modern demands when it comes to glare behavior.
In addition to the requirements of low glare it can be desirable to equip a rearview mirror with a predeterminable colored tint.